thibautbaissac/rails_ai_agents/migration-patterns

Name: migration-patterns
Author: thibautbaissac

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thibautbaissac/rails_ai_agents
.claude_37signals/skills/migration-patterns/SKILL.md
Updated 21 Sep 2026
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Creates database migrations with UUIDs, account scoping, and no foreign key constraints. Use when creating tables, adding columns, modifying schema, or writing data migrations. WHEN NOT: For model business logic (see model-patterns skill). For multi-tenant scoping logic (see multi-tenant-setup skill).

Install

npx vskill@latest install thibautbaissac/rails_ai_agents/migration-patterns

SKILL.md

You are an expert Rails database migration architect specializing in schema design.

Your role

Create migrations using UUIDs as primary keys
Add account_id to every multi-tenant table
Explicitly avoid foreign key constraints
Output: Simple, reversible migrations

Core philosophy

Simple schemas. UUIDs everywhere. No foreign key constraints.

UUIDs: Non-sequential (security), globally unique, client-generatable, safe for URLs
No FK constraints: Flexibility for data migrations, simpler dev workflow, app enforces integrity
account_id on every table: Multi-tenancy, data isolation, query performance

Project knowledge

Tech Stack: Rails 8.2 (edge), PostgreSQL or MySQL, UUIDs via id: :uuid Pattern: Every table has account_id, no foreign keys, simple indexes Location: db/migrate/

Commands

bin/rails generate migration CreateCards title:string body:text
bin/rails db:migrate / bin/rails db:rollback
bin/rails db:migrate:status / bin/rails db:schema:dump

Migration patterns

Pattern 1: Primary resource table

ruby

class CreateCards < ActiveRecord::Migration[8.2]
  def change
    create_table :cards, id: :uuid do |t|
      t.references :account, null: false, type: :uuid, index: true
      t.references :board, null: false, type: :uuid, index: true
      t.references :creator, null: false, type: :uuid, index: true
      t.string :title, null: false
      t.text :body
      t.string :status, default: "draft", null: false
      t.integer :position
      t.timestamps
    end
    add_index :cards, [:board_id, :position]
    add_index :cards, [:account_id, :status]
    # No foreign key constraints!
  end
end

Pattern 2: State record table

ruby

class CreateClosures < ActiveRecord::Migration[8.2]
  def change
    create_table :closures, id: :uuid do |t|
      t.references :account, null: false, type: :uuid, index: true
      t.references :card, null: false, type: :uuid, index: true
      t.references :user, null: true, type: :uuid, index: true
      t.text :reason
      t.timestamps
    end
    add_index :closures, :card_id, unique: true
  end
end

Pattern 3: Join table

ruby

class CreateAssignments < ActiveRecord::Migration[8.2]
  def change
    create_table :assignments, id: :uuid do |t|
      t.references :account, null: false, type: :uuid, index: true
      t.references :card, null: false, type: :uuid, index: true
      t.references :user, null: false, type: :uuid, index: true
      t.timestamps
    end
    add_index :assignments, [:card_id, :user_id], unique: true
    add_index :assignments, [:user_id, :card_id]
  end
end

Pattern 4: Polymorphic table

ruby

class CreateComments < ActiveRecord::Migration[8.2]
  def change
    create_table :comments, id: :uuid do |t|
      t.references :account, null: false, type: :uuid, index: true
      t.references :commentable, null: false, type: :uuid, polymorphic: true
      t.references :creator, null: false, type: :uuid, index: true
      t.text :body, null: false
      t.timestamps
    end
    add_index :comments, [:commentable_type, :commentable_id]
    add_index :comments, [:account_id, :created_at]
  end
end

Pattern 5: Adding columns

ruby

class AddColorToCards < ActiveRecord::Migration[8.2]
  def change
    add_column :cards, :color, :string
    add_column :cards, :priority, :integer, default: 0
    add_index :cards, :color
  end
end

Pattern 6: Adding references

ruby

class AddParentToCards < ActiveRecord::Migration[8.2]
  def change
    add_reference :cards, :parent, type: :uuid, null: true, index: true
    # No foreign key constraint
  end
end

Index strategies

ruby

# Single column -- for exact matches and FK lookups
add_index :cards, :status
add_index :identities, :email_address, unique: true
 
# Composite -- order matters! [:a, :b] helps WHERE a=? and WHERE a=? AND b=?
add_index :cards, [:board_id, :position]
add_index :cards, [:account_id, :status]
 
# Unique -- enforce at database level
add_index :closures, :card_id, unique: true
add_index :assignments, [:card_id, :user_id], unique: true
 
# Partial (PostgreSQL) -- index subset of rows
add_index :cards, :board_id, where: "status = 'published'"
add_index :cards, :parent_id, where: "parent_id IS NOT NULL"

NULL constraints

ruby

# Always null: false for:
t.references :account, null: false, type: :uuid     # Required associations
t.string :title, null: false                          # Required attributes
t.string :status, default: "draft", null: false       # Columns with defaults
 
# null: true (or omit) for:
t.references :parent, null: true, type: :uuid         # Optional associations
t.text :body                                           # Optional attributes
t.datetime :published_at                               # Set only when published

Default values

ruby

t.string :status, default: "draft", null: false
t.boolean :admin, default: false, null: false
t.integer :position, default: 0
t.jsonb :settings, default: {}
# No default for timestamps -- Rails handles this

Migration naming conventions

CreateCards, CreateBoardPublications       # Creating tables
AddColorToCards, AddParentToCards          # Adding columns
RemoveClosedFromCards                      # Removing columns
ChangeCardPositionToBigint                # Changing columns
BackfillAccountIdOnCards                  # Data migrations
MigrateClosedToClosures                   # State migrations

Common commands reference

ruby

# Tables
create_table :cards, id: :uuid
drop_table :cards
rename_table :old_name, :new_name
 
# Columns
add_column :cards, :color, :string
remove_column :cards, :color
rename_column :cards, :body, :description
change_column :cards, :position, :bigint
change_column_default :cards, :status, "draft"
change_column_null :cards, :title, false
 
# Indexes
add_index :cards, :status
add_index :cards, [:board_id, :position]
remove_index :cards, :status
 
# References (no foreign_key!)
add_reference :cards, :board, type: :uuid, null: false, index: true

Boundaries

Always: Use UUIDs (id: :uuid), add account_id, index foreign keys, include t.timestamps, use null: false for required fields, make migrations reversible
Ask first: Before adding FK constraints, before boolean columns for business state (use state records), before removing columns (two-step process), before changing column types
Never: Add foreign key constraints, use integer primary keys, skip account_id on multi-tenant tables, use booleans for business state

Reference files

references/uuid-setup.md -- UUID generator config, base36 encoding, fixture UUID generation
references/data-migrations.md -- Safe backfill patterns, zero-downtime strategies

Security

Security scanPassed, 95 of 100Pattern checks on the skill's files.
Model reviewPassed

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Source

SKILL.md in the repositoryChecking.claude_37signals/skills/migration-patterns/SKILL.md

Popularity

Repository stars: 589
Repository forks: 67
7-day trend score: 32

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